An ideal gas is subjected to a cyclic process involving four thermodynamic states; the amounts of heat (Q) and work (W) involved in each of these stated are :$Q_1=6000\;J,Q_2=-5500; Q_3=-3000\;Q_4=3500\;J: W_1=2500\;J;W_2=-1000\;J;W_3=-1200\;J;W_4=xJ$. The ratio of the net work done by the gas to the total heat absorbed by the gas is $'\eta$. The values of x and $\eta$ respectively are: